New dawn for thorium reactor research

First molten-salt thorium nuclear reactor experiment in over 45 years starts in the Netherlands

Petten researchers prepare to place the crucibles containing thorium salt into the reactor Credit: Thorium Energy World

The first phase of the Salt Irradiation Experiment (SALIENT) has begun at the Nuclear Research and Consultancy Group in Petten, a nuclear research facility on the Dutch North Sea coast. The experiment is being carried out in cooperation with the European Commission Laboratory Joint Research Center-ITU (JRC) in Karlsruhe, Germany, and initially aims to produce cleaner reactor fuel, and will then look at materials for reactor construction. The last research into molten salt thorium reactors was carried out at the Oak Ridge laboratory in the US.

Inside the high flux reactor Credit: Thorium Energy World

The Petten team is using the site’s high flux reactor under product manager Sander DeGroot and lead scientist Ralph Hania. Using the high heat inside the reactor, the team is melting a sample of thorium salt fuel — a mixture of lithium fluoride and thorium fluoride — inside an insulated graphite crucible, and over time the neutron bombardment will trigger nuclear reactions that will transmute the thorium in the sample into uranium isotopes that can undergo nuclear fission.

The team’s first task is to remove noble metals (that is, those which are not involved in the reactions) to make a more efficient fuel; they are trying two methods for this, using a nickel foil in one crucible and a cube of highly porous nickel in another, hoping that the noble metals will preferentially precipitate out onto the nickel. The JRC is providing the thorium salts for the project and will analyse the fission products after irradiation to assess their stability. This stage will feed into later research into how to deal with the waste from a molten salt thorium reactor.

The next stage of the project will use a different fuel mixture also containing beryllium, known as FlIBe, which is believed to be the best mixture for a working thorium nuclear reactor (the mixture without beryllium is designed for a specific type of reactor that ‘burns’ nuclear waste from conventional nuclear reactors). This phase will test the resilience to corrosion and high operating temperatures of materials to be used in the construction of molten salt thorium reactors, such as different grades of steel, the nickel alloy Hastelloy (which was used at Oak Ridge) and titanium-zirconium-molybdenum alloys.

In later stages, the team plans to install systems circulating molten salt around loops; the Petten high-flux reactor is one of few in the world large enough for this. “This is a technology with much perspective for large scale energy production,” de Groot commented. “We want to have a head-start once the technology will break through.”

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This looks promising. The Liquid Fluoride Thorium Reactor has several advantages. It is easier to control than a uranium cycle, can be failsafe, runs at a high temperature for good thermal efficiency and although the waste is radioactively hot, it decays more quickly. It is also a source of gamma radiation and this makes difficult to use for weapons.

I hope you are right. But, unfortunately the business model is not as profitable. Liquid thorium can be supplied by a low cost supplier. Current Uranium reactors are locked into very expensive machined fuel rods. Like when Polaroid used to lock camera owners into buying their expensive film.

You are quite right – the money for LFTR is not in supplying the fuel, like it is for LWRs. I believe the money will be in mass producing the small-sized reactors in a factory, where each power plant site has multiple reactors. Reactors that use graphite as a moderator will need to be replaced as the graphite degrades after several years, which would be the sustaining side of the business model. At least, that is how I picture it.

If our reactors are so untried, I wish we would look at the Thorium based process instead of the ‘press on regardless’ we have with the new fleet of Hinckley etc. We could achieve a good base load generation system using smaller scale, cleaner, safer nuclear plants.

The biggest weakness of uranium is that it’s difficult to separate the different isotopes, firstly to make the fuel (enrichment) and then after to manage the waste, requiring a plant bigger than the PowerStation. (I.e. hundreds centrifuges or miles of diffusion pipes.)

Whereas Thorium pre and post processing is simple chemistry, making it simpler and safer.

The weakness of Uranium is the high pressure water cooled reactors PWR with solid fuel rods. The revolution here is the molten salt reactor MSR which can use uranium and thorium with much greater efficiency, safety, economy and much cleaner. This is one of the first next generation reactors which will change the worlds energy supply.

Several reasons: there’s a lot more thorium than uranium, and it’s cheaper; the thorium route is less suitable for nuclear proliferation, and thorium reactors are believed to be better for disposing of nuclear waste.

This being a Dutch project with German involvement, nobody’s delaying Hinkley C.

It’s a matter of isotopes. Thorium transmutes to fissile U235 directly and can be easily (chemically) separated whereas natural Uranium contains only 0.7% U235 which required centrifuges to separate from U238, which are chemically identical.

Actually, Th232 is a fertile isotope that gets converted into U233, with a very small portion converted into U232. Those two isotopes are nearly inseparable, and the U232 gives off strong radiation along with its daughter decay products – which gives strong non-proliferation deterrance.

If nothing else, the fact that only a small part of the Thorium is converted to Uranium at any time (it is a breeder reaction that creates the fissile Uranium from the fertile Thorium) so there is much less ‘excess energy’ to drive overheating.

Hinkley C will be on hold anyway as EDF haven’t got any cash. 11 reactors are planned to be closed in France.
As has been said before, if the Cold War hadn’t pushed for sources of weapons-grade plutonium, we would have pushed for clean continuous Thorium energy and might not even have needed to deflate the North Sea and Maggie wouldn’t have needed to kill off the miners and seal the pits.

You are using a molten thorium salt as the fuel and the uranium (U233) produced carries on the burning. Present uranium based reactors use a solid fuel (U238 and U235).

When the soild fuel rods get contaminated with actinides (fill up with non U238 and U235 fission products), you end up with hundreds of tonnes of “spent nuclear fuel” which is not really spent, it’s just contaminated to the point where neutron absorption is too high to sustain the heat output required to heat the water to make the steam to spin the turbine to…. (Then you still have to store this contaminated solid U238 and U235 fuel for many thousands of years…. +10,000)

Not so with the Thorium molten salt cycle…. You can actually remove the contaminants online (mainly Pa233 to avoid the nasty U232) and you end up with a tiny fraction of volume (c.f. U fuel) of real waste that you have to handle for at most ~300 years… Roughly 1 % (i.e. 1 kg vs 100 kg)

You also need to add a small amount of U235 or Pu239 (between 1% to 2.5%) to start the Th/U232 process.

The latest information we have is that there are no thorium reactors in Russia. China, India and Indonesia have ongoing government-sponsored thorium programmes, and there are privately-funded efforts underway in the US, which The Engineer has reported on. As far as we are aware, there are currently no operational thorium reactors at any stage of development.

If as the experts claim Thorium Reactors are far safer than Uranium types, then we should embrace the technology. I saw something on the web a year ago that India has an experimental Thorium Reactor in operation already? Tidal is the answer anyway. Guaranteed clean power! The moon’s not leaving us, it just needs our leaders to get their fingers out!!

A Uranium burning molten salt reactor is arguably much safer than a Uranium breeding reactor as they do not require the coolant/fuel/moderator/waste products to be extracted during operation for processing.

Molten salt reactors may work, they may offer some fundamental cost benefits when fully developed.

1: This isn’t a real problem nobody has ever hidden a nuclear bomb programme in a civil power programme because it is far easier and cheaper to just build a clandestine bomb making programme with either centrifuges or a carbon/heavy water moderated reactor.
2: Thorium doesn’t reduce the proliferation risk to zero (it is arguable whether it really reduces the risk at all), as a result you will have to do precisely the same inspections and procedural controls as at a conventional plant, however you will have to develop new and different ones at additional cost!
3: The actual costs of compliance with nuclear non proliferation are pretty much a rounding error in their contribution to the current cost of nuclear power.

To summarise molten salt reactors does not equal thorium, do not conflate the benefits and costs!

Thorium gives pretty minor benefits while creating costs at every stage of the nuclear fuel cycle, we aren’t running out of uranium, as such a point in time we do start running out may then look at thorium!

I agree with you. Almost every advantage of LFTRs come from the LF part of the name. The only real advantage thorium has is the unique decay chain that gives valuable nuclear material, and uranium has its own unique chain that produces its own usable materials. Nonetheless, thorium quintiples the available nuclear fuel and both supply chains should be exploited.

Smart meters will save precisely zero. They are there purely to benefit the energy suppliers by laying off all the meter readers, and by better planning the generation. As for green energy, given the land area required for enough effective wind turbines to match the output of just one Hinkley C, I don’t really see that as an advantage either.

Absolutely right, for too long the renewables sector has been focussed on the low hanging fruit of wind and solar PV but if we’re all going to be driving electric cars by2040 then tidal is the next easiest technology and has the advantage of consistency and predictability. Fusion is the ultimate solution. As the article on Elon Musks storage solution showed the other day, it isn’t a large scale solution at all.

I read some of the early reports on Alvin Weinberg’s work in the 1950’s and 60’s on molten salt thorium reactors. I continue to be impressed by what was achieved with the available materials of that time at Oak Ridge. What a pity that the (UK) nuclear industry seems to have lost its ability to lead and innovate over the intervening decades! Would our nuclear industry prefer to continue to sit on its backside whilst more enlightened competitors steal the show?
By the way, I agree with Ron Shilton on tidal power … it’s a no brainer!

Thanks Nick. One day maybe the penny will drop with our illustrious leaders!?? When the wind stops blowing and the sun is hidden on dark dank days (usually when we need the energy) the tide will still ebb and flow, and guess what, we’re an island, and surrounded by this amazing phenomenon!

About ten years ago, Oxford University presented a case study showing how typical energy demand curves could be very closely matched to potential tidal energy supply curves.
The moon is unlikely to be leaving orbit any time soon!
UK plc seems to represent a catalogue of missed opportunity …
If political parties were prepared to set aside their differences and agree on supporting long-term strategic infrastructure projects then we might see progress. Maybe in our lifetime???

I worked with a firm of consulting engineers in 1980 on a water treatment plant. At that time they were also designing a tidal power scheme to be installed somewhere in the UK. It never happened. Not sure why but thirty odd years is a long time to wait!

At last a serious step forward on the road to safe Thorium nuclear power.
Full Marks to Kirk Sorensen and his growing team of enthusiasts all across the world, for pushing for this technology to be adopted.
We need liquid salt Thorium reactors and fast.

Tidal is on its way. There are a number of installations from less than 10 different companies, slightly different technologies, of around 2-3 MW each, operational or close to it. The amount of usable tidal depends very much on what tidal flow velocities are usable. So far tidal can only ever supply a small percentage of load even in sea-contiguous countries – maybe 10% in the extreme. They also require storage, adding cost.The result is that they have marginal competitiveness at best at the present time.
Wave, in which I have soldiered in R&D for 8 years now, is much father away, if it can ever become grid-competitive. There isn’t any wave technology that yet remotely approaches grid competitiveness.
Offshore wind should probably be seen as the competitive target.
So I suggest the thorium developments, that seem to avoid many negatives of nuclear, should be strongly pursued.

The thorium movement is growing every day when more and more people learn of this awesome technology. Thorium, especially in an MSR, has the potential to solve almost every one of the current problems with nuclear fusion – now we just need to convince the people with all the money and and the power to make changes to the existing system and of course the legislation,
I fear it is an uphill struggle, as the people whos acutally making all the money from the existing reactors will not want all of this to happen.
For anyone whos interested, I can only recommend the book “Super fuel” by Richard Martin – very well written and informative as to the story of thorium.

I have to say firstly that I know very little about the science of nuclear technology, but from what I have read. Thorium reactors offer huge advantages over conventional uranium reactors, so I can’t understand why the technology hasn’t grown into mainstream consideration, what is holding it back?

Surely during the cold war governments opted for Uranium nuclear power generation because they also benefited from having nuclear material and know how for developing nuclear weapons. This was a long time ago so why has it taken this long to consider more cost efficient methods such as Thorium?

Very good news for advocates of Thorium MSR Technology and for those aware of the benefits this new Nuclear 2.0 Technology brings to the mix. The fundamental change from solid to Liquid fuel within a molten salt sustains far higher (more efficient) temperatures than the old steam driven Nuclear 1.0 Technology … all while operating at ambient pressure … making for safer; cheaper (with less onerous fabrication processes) base-load Energy supply that is well suited for simpler implementation as small modular reactors. Being in a molten state during normal operation it is inherently ‘walk-away-safe’ – if a forced shut-down condition occurs – the fuel within the reactor just solidifies … i.e. it cools down rather than having a melt-down. The closed cycle of the MSR is also much more effective in burn-up of the fuel. Basing the fuel on Thorium (fertile) – which transmutes to U233 (fissile) when bombarded with neutrons – means that the small amounts of waste remaining after burn-up has a decay chain that reaches background levels after only ~300 years. A much more acceptable safe storage period compared to the current Uranium, U235, (solid) fuel cycle at 10’s of 1000’s of years of ‘safe’ storage required. And here’s where another great benefit in MSR Technology helps with the incumbent legacy of the Uranium fuel cycle … the ‘waste’ can be used within the fuel mix to provide the neutrons required to kick-start the Thorium reaction … a win-win situation to remove the stock-piles of radioactive ‘waste’ from the environment.

The team in the Netherlands seem to pick up & re-trace where the Molten Salt Reactor Experiment (MSRE), led by Alvin Weinberg in the late 60’s early 70’s, left off with their sub 10MW generator load (I believe was the max the experimental licence would permit at the time). No doubt much time and practical working knowledge has been lost between the MSRE programme being shelved in the early 70’s and now … which I presume is the reason for having to retrace and verify results of the previous experiment. Kirk Sorensen has been mentioned in the posts and the Fuel/Salt mix described bears his trade mark, Flibe Energy, and would be surprised if he has not been consulted with his great expertise in this field for the MSR concept, and in particular, the Liquid Fluoride Thorium Reactor (LFTR).

The potential for this as a major contributor to smaller/more localised base-load energy generation – without the need to have large investment in grid-systems that mar the countryside – must be viewed as a game changer in provision of cheap sustainable energy. This is especially the case where the landscape for transport shifts from fossil fuel driven to electrical driven transport.

There still seems to be an adversarial factionism in play – “tidal is the answer anyway”; “would much rather see the time money & effort spent on fusion research rather than fission”; and in other forums, wind power / solar is the only answer. The reality is that in order to successfully phase out fossil fuels and to support the considerable increase in production of clean electricity that this will entail, ALL effective solutions will have to be employed. At least one generation of new fission reactors will be required before fusion could possibly become an alternative, and wind, solar, etc. can only be part of the answer. Thorium cycle reactors are a no brainer and should have been developed already (would have, if Politicians were not so short sighted). Also, carry on with wind / solar / wave / fusion development as well.

windmills – think about the poor birds.
solar – all those panels -doesn’t it spoil the view……
fracking – think about the newts and the earthquakes…and the taps that light up.
tidal – think about the fishes and sea- creatures -getting squashed
fossil fuels – ohh – think about the emissions -acid rain …..
nuclear – end of the world !
I am done with electricity……over rated product …..to much hassle… going back to my cave ….
If only …..

I hope this reactor demonstrates the advantages of MSR reactors and it is used to test materials, chemistry, safety, economy and components next generation reactors. This reactor demonstrates that MSR are not just fantasy. Most of the next generation reactors will be in India and China. Many components and designs will come from Europe and the USA but China and India will dominate the building and design of future reactors. If / when wind,/ wave and solar power fails this MSRs will bridge or backup to low carbon energy. I would like to know a lot more about this reactor and its progress.

The MOLTEX project will eventually allow for a Thorium MSR . At present, this company has established patents covering their static tube in molten salt coolant medium.
Their pilot project is a Waste Burner fast reactor using Uranium and Plutonium chlorides.
They claim that ,the viscosity of the molten salt being very low, that heat transfer is feasible by convection. Ambient pressure, no combustibles or explosives, small pumps, high delivery temperature……all sorts of good things.
Read the patent document. https://www.moltexenergy.com/news/details.aspx?positionId=14
and wonder why nobody thought of this before.